A Trajectory Analysis using the ICESat2 Satellite¶
Overview of the steps involved:
Get very high-fidelity orbit trajectory information of the primary satellite:
This can be done using a POD-reduced dynamics run in which all empirical accelerations and other parameters are used to compensate for any mismodelled forces.
This has already been done for our purposes.
Do a run of GEODYN in which the orbit trajectory IS the tracking datatype (PCE).
Use this run type to do all density model assessments
The residuals will be the difference from the truth.
Methods for assessing the density models (using trajectory run type):
General fit (residuals and RMS)
Arc overlap
If any arcs overlap, look at how well different density models provide consistency between overlapping arcs
Test of prediction - Do a fit from t1 to t2 and then predict to some t3. If the density model is better, the difference between predicted orbit (t2 to t3) and the precise trajectory (PCE data) will contain how well the model is doing.
Step 0: Pre-processing the PCE data into a G2B file¶
We will construct a G2B_PCEfile from a set of binary .rvg files which contain trajectory output from a reduced-dynamics run of GEODYN. The files will be stitched together to create a the GEODYN-specific, trajectory-based tracking data type (called PCE (Precice-Clock-Error) ) and stored in a G2B file.
Each .rvg file contains a 30-hour arc of ICESat2 trajectory data. These datasets are the output from a very precise run of GEODYN in which the orbit has been determined very well (to a few centimeters accuracy) using a reduced dynamics technique (empirical accelerations and other parameters are adjusted to account for any mismodelled forces).
The process that takes place in pygeodyn is as follows: 1. dump the data from each arc into a usable format 2. chop of the 3 hour padding on the ends to eliminate discontinuities from end effects 3. stitch together all the files 4. smooth over any existing discontinuities between arc gaps or maneuvers. 5. All data is placed in a single TRAJ.txt file which is then fed into a Fortran script (pce_converer.f) which converts the data into a G2B file to be ingested on fort.40 of
the GEODYN run.
PygeodynPreprocessing¶
[1]:
import copy
[2]:
%load_ext autoreload
%autoreload 2
import sys
sys.path.insert(0,'/data/geodyn_proj/pygeodyn/utils_pygeodyn_develop/util_preprocessing/')
from PYGEODYN_Preprocess import PygeodynPreprocessing
path_to_prep_directory = '/data/data_geodyn/inputs/icesat2/pre_processing'
path_to_binaryrvg = '/data/data_geodyn/inputs/icesat2/pre_processing/traj_files_rvg'
arc1_files = [
'orbit.1807001.2018.312',
'orbit.1807001.2018.313',
'orbit.1807001.2018.314',
'orbit.1807001.2018.315',
'orbit.1807001.2018.316',
'orbit.1807001.2018.317',
'orbit.1807001.2018.318',
# 'orbit.1807001.2018.319',
# 'orbit.1807001.2018.320',
# 'orbit.1807001.2018.321',
# 'orbit.1807001.2018.322',
]
##### Uncomment the below call to overwrite the G2B data by re-running the pre-processing code
# Obj = PygeodynPreprocessing(path_to_binaryrvg, path_to_prep_directory, arc1_files)
# Obj.run_preprocess_PCE()
Step 1: Run GEODYN using Pygeodyn with the ICESat2 configuration¶
As a reminder, PYGEODYN is called with the PYGEODYN class, but modifications to the ICESAT2 configuration are largely controlled through the Satellite_ICESat2 class in the PYGEODYN_Satellites.py file. Please refer to this file first for file structure setups and modifications to the Pygeodyn structure.
Step 1.1: Run with MSIS2¶
[3]:
### Identify which arcs you want to run:
arcs_files = [
'2018.313', # 1
'2018.314', # 2
'2018.315', # 3
'2018.316', # 4
'2018.317', # 5
# '2018.318', # 6
# '2018.319', # 7
# '2018.320', # 8
# '2018.321', # 9
# '2018.322', # 10
]
#------ A dictionary containing the run parameters ------
run_params = {}
run_params['arc'] = arcs_files
run_params['satellite'] = 'icesat2'
run_params['den_model'] = 'msis2'
run_params['SpecialRun_name'] = '_TrajAnalysis'
run_params['verbose'] = False
run_params['action'] = 'run'
[4]:
%load_ext autoreload
%autoreload 2
sys.path.insert(0, '/data/geodyn_proj/pygeodyn/utils_pygeodyn_develop/')
from PYGEODYN import Pygeodyn
#### ---------------------------------------------
####
#### ----------------- RUN MSIS2.0 ---------------
####
#### ---------------------------------------------
##### Use copy.deepcopy to copy all levels of dictionary and
### allow modification of new variable
run_params1 = copy.deepcopy(run_params)
run_params1['den_model'] = 'msis2'
# ### Run pyeodyn for the arcs in the above set.
# Obj_Geodyn = Pygeodyn(run_params1)
# Obj_Geodyn.RUN_GEODYN()
The autoreload extension is already loaded. To reload it, use:
%reload_ext autoreload
Step 1.2: Run with DTM87 for comparison¶
[5]:
%load_ext autoreload
%autoreload 2
sys.path.insert(0, '/data/geodyn_proj/pygeodyn/utils_pygeodyn_develop/')
from PYGEODYN import Pygeodyn
#### ---------------------------------------------
####
#### ------------------- RUN DTM -----------------
####
#### ---------------------------------------------
##### Use copy.deepcopy to copy all levels of dictionary and
### allow modification of new variable
run_params2 = copy.deepcopy(run_params)
run_params2['den_model'] = 'dtm87'
### Run pyeodyn for the arcs in the above set.
# Obj_Geodyn = Pygeodyn(run_params2)
# Obj_Geodyn.RUN_GEODYN()
The autoreload extension is already loaded. To reload it, use:
%reload_ext autoreload
Step 1.2: Run with Jaachia 71 Model for comparison¶
[6]:
%load_ext autoreload
%autoreload 2
sys.path.insert(0, '/data/geodyn_proj/pygeodyn/utils_pygeodyn_develop/')
from PYGEODYN import Pygeodyn
#### ----------------------------------------------
####
#### ----------------- RUN JAACHIA -----------------
####
#### ----------------------------------------------
##### Use copy.deepcopy to copy all levels of dictionary and
### allow modification of new variable
run_params3 = copy.deepcopy(run_params)
run_params3['den_model'] = 'jaachia71'
##### Run pyeodyn for the arcs in the above set.
# Obj_Geodyn = Pygeodyn(run_params3)
# Obj_Geodyn.RUN_GEODYN()
The autoreload extension is already loaded. To reload it, use:
%reload_ext autoreload
Read GEODYN Output using PygeodynRead functionality¶
Get MSIS2 Data¶
[8]:
%load_ext autoreload
%autoreload 2
import sys
sys.path.insert(0, '/data/geodyn_proj/pygeodyn/utils_pygeodyn_develop/')
from PYGEODYN import Pygeodyn
#------ A dictionary containing the run parameters ------
run_params1 = {}
run_params1['arc'] = ['2018.313',
'2018.314',
'2018.315',
'2018.316',
'2018.317',
]
run_params1['satellite'] = 'icesat2'
run_params1['den_model'] = 'msis2'
run_params1['SpecialRun_name'] = '_TrajAnalysis_1'
run_params1['verbose'] = False
run_params1['action'] = 'read'
Obj_Geodyn1 = Pygeodyn(run_params1)
Obj_Geodyn1.getData()
The autoreload extension is already loaded. To reload it, use:
%reload_ext autoreload
=================================================================
Initializing PYGEODYN to ...
... READ GEODYN output
=================================================================
Loading ... icesat2_2018313_54hr.msis2
Loading ... icesat2_2018314_54hr.msis2
Loading ... icesat2_2018315_54hr.msis2
Loading ... icesat2_2018316_54hr.msis2
Loading ... icesat2_2018317_54hr.msis2
Get DTM87 Data¶
[9]:
%load_ext autoreload
%autoreload 2
from PYGEODYN import Pygeodyn
import copy
run_params2 = copy.deepcopy(run_params1)
run_params2['den_model'] = 'dtm87'
Obj_Geodyn2 = Pygeodyn(run_params2)
Obj_Geodyn2.getData()
The autoreload extension is already loaded. To reload it, use:
%reload_ext autoreload
=================================================================
Initializing PYGEODYN to ...
... READ GEODYN output
=================================================================
Loading ... icesat2_2018313_54hr.dtm87
Loading ... icesat2_2018314_54hr.dtm87
Loading ... icesat2_2018315_54hr.dtm87
Loading ... icesat2_2018316_54hr.dtm87
Loading ... icesat2_2018317_54hr.dtm87
Get Jaachia 71 Data¶
[10]:
%load_ext autoreload
%autoreload 2
from PYGEODYN import Pygeodyn
# import copy
run_params3 = copy.deepcopy(run_params1)
run_params3['den_model'] = 'jaachia71'
Obj_Geodyn3 = Pygeodyn(run_params3)
Obj_Geodyn3.getData()
The autoreload extension is already loaded. To reload it, use:
%reload_ext autoreload
=================================================================
Initializing PYGEODYN to ...
... READ GEODYN output
=================================================================
Loading ... icesat2_2018313_54hr.jaachia71
Loading ... icesat2_2018314_54hr.jaachia71
Loading ... icesat2_2018315_54hr.jaachia71
Loading ... icesat2_2018316_54hr.jaachia71
Loading ... icesat2_2018317_54hr.jaachia71
Analyze output¶
Our analysis has the following output products:
Residuals of the POD across many arcs
RMS of fit of the POD across many arcs
Adjustment of the drag coefficient (drag acceleration to compensate for inaccuracies in the density model.)
Check of consistency (in the residuals) across overlapping arc times
RMS of the overlapping residual difference (this removes the PCE contribution) Using the
Orbfil:From ORBFIL grab the overlapping ephemeris and difference the two models. Compare this against the same of prediction
How well does the predicted time period match up with the determined ephemeris (see this in the resids of the two).
Calculate and plot the radial component of the trajectory
[11]:
import plotly.graph_objects as go
from plotly.offline import plot, iplot
from plotly.subplots import make_subplots
import plotly.express as px
config = dict({
'displayModeBar': True,
'responsive': False,
# 'staticPlot': True,
'displaylogo': False,
'showTips': False,
})
1. Residuals of the POD across many arcs¶
Resids = PCE - POD Trajectory
[12]:
%load_ext autoreload
%autoreload 2
from PYGEODYNAnalysis_icesat2PCEtrajectory import plot_residual_meas_summary
from PYGEODYNAnalysis_icesat2PCEtrajectory import rms_summary_table
Obj_list = [Obj_Geodyn1,Obj_Geodyn2,Obj_Geodyn3,]
rms_summary_table(Obj_list)
fig = make_subplots(rows=2, cols=1,
subplot_titles=(["Mean Residuals per Arc", 'RMS of Fit per Arc']),
vertical_spacing = 0.1)
fig = plot_residual_meas_summary(fig, Obj_Geodyn2, 0)
fig = plot_residual_meas_summary(fig, Obj_Geodyn3, 1)
fig = plot_residual_meas_summary(fig, Obj_Geodyn1, 2)
fig.show(config=config)
The autoreload extension is already loaded. To reload it, use:
%reload_ext autoreload
+———————————————————+—————————————————————————+————————————————+
| Summary Across all Arcs |
+———————————————————+—————————————————————————+————————————————+
+ Density Model + Mean Residual (cm) + RMS of Fit +
+-------------------+-------------------------+----------------+
+ msis2 + -4.54000e+01 + 1.82780e-01 +
+ dtm87 + -1.27800e+02 + 2.45000e-01 +
+ jaachia71 + 9.80000e+00 + 3.22620e-01 +
+———————————————————+—————————————————————————+————————————————+
[13]:
%load_ext autoreload
%autoreload 2
from PYGEODYNAnalysis_icesat2PCEtrajectory import plot_residuals_observed
fig = make_subplots(rows=3, cols=1,
subplot_titles=(['X', 'Y', 'Z']),
vertical_spacing = 0.1,
)
fig = plot_residuals_observed(fig, Obj_Geodyn2, 0)
fig = plot_residuals_observed(fig, Obj_Geodyn3, 1)
fig = plot_residuals_observed(fig, Obj_Geodyn1, 2)
fig.update_layout(title="Observation Residuals (PCE - Observed , T.O.R.)")
fig.show(config=config)
The autoreload extension is already loaded. To reload it, use:
%reload_ext autoreload